The invention relates to power transmission belts, and more particularly to flexible drive ring belts having a flexible drive ring comprising segments and a tensile member.
It is well known in the art that a gear type transmission may be used for running a motor vehicle, motorcycle or the like. However, gear type transmissions generally have a fixed number of gears. They are usually designed to operate most efficiently in one of the gears, leaving the others to cause the engine to run at less efficient operating points. Consequently, for the purpose of improving efficiency a continuously variable transmission, CVT, is preferable. CVT transmissions require belts specially adapted for such use.
Various types of power transmission belts have been developed for use in continuously variable transmissions, or CVT""s.
Generally, CVT belts have a silhouette similar to that of a conventional V-belt. In particular, they are broad at the top and narrow at the bottom and designed to fit between the sheaves of a pulley defining an angular groove. The pulley on which the belt is trained generally will comprise a moveable sheave and a fixed sheave, each having a truncated cone shape. Generally, one of the sheaves moves while the other remains fixed.
Moving one sheave in relation to the other varies the effective diameter xcfx86 of the pulley within which the belt operates. Belt speed is a function of the effective diameter of the pulley that is, in turn, a function of the axial position of the sheaves relative to each other.
CVT type belts in the prior art include belts comprising a plurality of blocks connected transversely to a tensile member. Certain forms of cog type belts are also known.
Representative of the art is U.S. Pat. No. 4,595,387 (1986) to McComber which discloses a V-block type belt with polymeric portions oriented transversely to the belt. The polymeric portions are fixedly connected along a longitudinal axis of the belt at predetermined intervals.
The prior art teaches fixing the position of transverse blocks relative to a tensile load carrying member. Consequently, the prior art teaches the use of transverse blocks constructed to precisely mechanically connect with the tensile member. Relative movement of the components is strictly controlled.
Also representative of the art is U.S. Pat. No. 4,734,085 (1988) to Takashima et al. which discloses a v-belt to be used in a dry type transmission comprising an endless load carrier having a series of cogs by which transversely mounted blocks are engaged to the load carrier.
The prior art belts have the effect of concentrating bending forces experienced by the tensile member at those points where the tensile member contacts each segment. In operation, repeated flexing at these locations cause tensile cord failure. Generally, the prior art belt construction is one of an interconnected, relatively stiff assembly. The segments are attached to flexible tensile member by clamping or through some form of interference fit.
What is needed is a flexible drive ring belt having a flexible drive ring. What is needed is a flexible drive ring belt having a tensile member cooperatively engaged with the flexible drive ring. What is needed is a flexible drive ring belt having a flexible drive ring comprising a plurality of fixed ring segments that are not fixed to a tensile member. What is needed is a flexible drive ring belt having an elastic member for preloading the flexible drive ring. The present invention meets these needs.
The primary aspect of the present invention is to provide a flexible drive ring belt having a flexible drive ring.
Another aspect of the invention is to provide a flexible drive ring belt having a tensile member cooperatively engaged with the flexible drive ring.
Another aspect of the invention is to provide a flexible drive ring belt having a flexible drive ring comprising a plurality of ring segments that are not fixed to a tensile member.
Another aspect of the invention is to provide a flexible drive ring belt having an elastic member for preloading the flexible drive ring.
Other aspects of the invention will be pointed out or made apparent by the following description of the invention and the accompanying drawings.
The invention comprises a flexible drive ring CVT belt. It comprises a flexible drive ring having a plurality of adjacent ring segments. The segments comprise metallic or non-metallic material sufficient to bear a compressive load imposed by CVT sheaves. The segments are interlocked along a longitudinal axis and are preloaded in the assembled position by an elastomeric member. A tensile member or belt bears on an outer circumfrential bearing surface formed by the interlocked segments. The tensile belt may comprise any belt known in the art, for example a multi-ribbed power transmission belt. The tensile belt is moveable along a longitudinal axis on the circumfrential bearing surface. The segments further comprise opposing inclined surfaces for engaging sheave surfaces on a pulley.